Abstract

Layering of water molecules on the surface of alumina nanoparticles in an alumina/water nanofluid is studied using nuclear magnetic resonance(NMR). The data suggest that a thin ordered layer of water molecules surrounds each nanoparticle. This ordered layer increases the nanoparticle effective volumetric fraction; however, the nanofluid thermal conductivity appears to be unaffected by this layer, and in good agreement with Maxwell’s effective medium theory. Furthermore, the NMR data suggest that the nanoparticles do not enhance, but rather stifle micromixing in the base fluid.

Received 31 August 2009Accepted 01 December 2009Published online 22 December 2009

Acknowledgments:

C.G.’s doctoral project was supported by the King Abdulaziz City of Science and Technology Grant No. 014914–002 (KACST, Saudi Arabia). Troy Borneman, Jonathan Hodges, and Sekhar Ramanathan of the Cory Laboratory are thanked for advice and assistance with the NMR measurements.